Reinforced concrete structures may be vulnerable to progressive collapse due to lack of sufficient continuous reinforcement. In most guidelines, general structural integrity requirements to reduce progressive collapse have been introduced, but the design of structures against progressive collapse has not been a major consideration. A mitigation scheme is proposed to increase resistance against progressive collapse. This involves the provision of additional reinforcement bars in the mid-layer of reinforced concrete beams. In the research reported here, four specimens were designed and tested subject to quasi-static loading conditions for a column removal scenario. One test specimen was made with conventional steel reinforcement and three specimens were made with additional steel reinforcement at the mid depth of the beam. The quasi-static behaviour of the test specimens were converted to a dynamic representation using an energy balance approach to obtain the progressive collapse load. Test results show that the proposed scheme significantly improves the ductility and collapse load of concrete beams subject to a column removal scenario.

The progressive collapse behaviour of reinforced concrete (RC) structures requires consideration of material and\ud geometric non-linearity, concrete crushing and rebar fracture. Compressive arch action (CAA) and catenary action\ud (CTA) are the main resisting mechanisms against progressive collapse following a column loss. Hence, many studies\ud have concentrated on the development of CAA and CTA in RC beams, but without considering the effect of bar\ud fracture and the reduction in beam effective depth due to concrete crushing. Taking these additional factors into\ud account, an analytical model to predict the structural behaviour of RC beams under a column removal scenario was\ud developed. The proposed model was evaluated and validated with the available experimental results. The evaluation\ud and validation indicate that the proposed model can provide a reliable assessment of RC beam capacity against\ud progressive collapse

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